Enhancement of the Development Efficiency of Water-Oil Zones

摘要

Virtually all oil pools are underlain by contour or bottom water. The presence of contour water enhances the formation of a water-oil zone (WOZ) of variable width. For instance, the WOZ is several kilometers wide in oilfields of the Ural-Volga region. It is remarkable that the thickness of the oil-saturated layer tends to zero as the external water-oil contour is approached. Because the water-oil zones occupy large areas, they contain significant reserves of hard-to-recover oil. Oil is particularly difficult for extraction near the external water-oil contour, where its specific reserve per unit area is insignificant. In this respect, if bottom water is present, oil-saturated formations near the external water-oil contour can be considered to be a WOZ that is confined to an oil pool with contour water, because they also include hard-to-recover oil reserves.